Any suggestions on resources for developing maps with realistic representation of global climate?

I've looked at a lot of 'world building guides' and world map software packages over the years, but have never found any that accurately reflected major climate forces. Most fictional world maps suffer similar problems.

For example, while I'm certainly not a professional climatologist, I know enough to cringe when I see hot deserts all along the equator... or on both sides of a mountain range. Ditto maps/guides that show consistent average temperatures at all longitudes of a given latitude... rather than having significant variations due to ocean currents like the warmth provided to NW Europe by the Gulf Stream or the cooling provided to Hawaii by water pulled down from the north. Similarly, some programs will generate water worlds with only scattered land... yet still have polar ice caps despite the increased greenhouse warming from all the water vapor those oceans would give off AND the lack of anything to anchor the ice in place. Et cetera.

This seems like something which there should be existing guides and/or computer tools for, but I've never seen any which didn't have enough glaring errors that you either had to say 'the climate is changed by magic' or they were more trouble than they were worth. Any suggestions short of tracking down one of the 'global climate models' used by the IPCC and adding a random terrain generator?

I have Campaign Cartographer www.profantasy.com/products/cc3.asp
and its worth the cost. It is time consuming as well but it will yield the best results. The new version came out recently, but I have not checked it out. This program will allow you to create a large, birds eye view of the world you create. However, it does not create detailed maps of towns, cities, taverns, castles, etc. you have to buy yet another version of that program to do that...

Adamantine Dragon, yes 'it is magic' can cover a lot of things, but unless you are modifying the laws of physics (which, as MagiMaster notes, can get very complicated) it isn't so much that the 'rules do not apply' as 'there is a magical alteration over here, but everything interacts with that alteration per normal physical laws'.

I'm fine with the 'Eye of Abednego' on Golarion or the 'Sea of Dust' on Oerth... because both are specifically 'magical' in origin. Yet if there were to be a 'natural' desert downwind of the 'Eye of Abednego' (or a rainforest downwind of the 'Sea of Dust') it would make no sense.

I'm just saying that if a map doesn't seem exactly right according to our current understanding of climate, it is always possible that there is some magic at play.

I completely agree that magic should be the exception and the world should otherwise try to follow plausible climate patterns.

In my world I just created my own continents and islands and put what "made sense" to me. I didn't really care if they followed some sort of climate rules guideline. That's in part because I'm not really convinced that we know enough about climate on our own world to really claim to understand how it should work on a completely different world which may or may not have comparable atmospheric composition, rotational dynamics, ocean currents or a hundred other things I could think of that might have a significant impact on climate. Climate is notoriously chaotic anyway, meaning it is heavily dependent on initial conditions. Something as simple as having a 65% instead of a 75% nitrogen percentage in the air could completely change our climate rules.

Do what seems plausible. I tend to spend my energy on the world's geopolitical and trade "rules" than on worrying if it makes sense for a desert to be adjacent to a swamp with those mountains only a hundred kilometers to the west...

I tend to spend my energy on the world's geopolitical and trade "rules" than on worrying if it makes sense for a desert to be adjacent to a swamp with those mountains only a hundred kilometers to the west...

Ah, but see... they are the same thing.

The "trade winds" here on Earth are generated by the downdraft portion of Hadley cell circulation... which are also responsible for most of the world's deserts. There is a direct link between the basic climate function of hot air near the equator rising, losing its water vapor content at high altitude, getting drawn back down once it has cooled (aka 'Hadley cells') and both the geographical areas with the best wind conditions for ocean trade AND the formation of deserts. The dry air coming down tends to push away storm fronts - providing clear sailing with strong prevailing winds over the oceans and areas of very low rainfall (i.e. deserts) over land.

Basically, 'trade rules' and 'geopolitics' are to a very large extent determined by climate.

As to climate being unknown and/or unknowable... not really. George Hadley, who worked out the details of 'Hadley cells' and their importance in forming the trade winds, has been dead for about three hundred years now. 'Hot air rises' isn't some random unpredictable concept and isn't going to change if the mixture of nitrogen to oxygen (or argon) in the atmosphere shifts 10%. Indeed, most factors influencing climate are similarly basic and clear cut. Weather is chaotic. Climate is not.

Thanks for the additional suggestions on mapping software. I think I looked at an old version of Campaign Cartographer years ago, but I'll check it again.

Actually, weather is chaotic. Climate tends to change slowly. Though I agree that our ability to predict the climate of an alien planet is pretty theoretical at this point (but that hasn't stopped people from making serious attempts).

Don't think so. By trade rules, in this context, I think AD is speaking of who is trading what with who for what; not, how do trade winds impact trade over long distances.

Kingdoms of Kalamar designers took great pride in their fantasy maps. They even did a whole hardcover atlas. Includes were trade winds, seasonal currents, the terrain features made sense. Rivers flowed right, etc. If there was one thing and only one thing they did right was have great geography and climate considerations. They practically built a campaign setting from the ground up based on such thing as their fantasy map and the temps. and rains from my understanding.

I don't know that there is a lot of guidelines for design. But I watch a lot geology/climate documentaries such as "How the Earth Was Made" etc. It sounds like you have a pretty solid foundation that if you are looking to design your own you shouldn't need guidelines. And if you want a game world already designed on those principles, check out Kingdoms of Kalamar ... or at least their Atlas.

One thing I have to admit that I did consider when creating my own world was the very pedestrian and utilitarian issue of having varying types of geography close enough that adventuring parties could plausibly move around and experience different types of terrain and climate.

I suppose some would accuse me of shamelessly metagaming. In one case I did create a desert in a place probably doesn't "make sense" but that desert was the result of an apocalyptic war between dragons, demons and the humanoid races, not natural climate effects.

Still, I think the end result was a quite plausible world.

By the way "trade winds" might very well be unique to this planet. Assuming that other planets would have them is simply an assumption. There's no "rule" or "climate model bias" towards winds which promote trade between nations. My world has "trade winds" because I wanted them, not because they "made sense" from a climate model perspective.

At some point in the design of the world, I decided to build the world as a gaming platform, not as a purely academic exercise in world building.